A Novel Biomass Photothermal Adsorbent for Simultaneous High‐Purity Thorium Recovery and Clean Water Production From Acidic Wastewater

ABSTRACT Thorium dioxide (ThO 2 ) is the key nuclear fuel of thorium‐based nuclear reactors. A significant amount of Th(IV) ions can be released into the wastewater during rare earth mining. These ions can be recovered and utilized as potential fuel resources. Moreover, producing clean water from these wastewaters could also alleviate water scarcity, but they still remain challenging. Here, novel polyphosphonate networks (PNs) from the facile thermal treatment of phytic acid are grown in situ onto wood substrates to develop a low‐cost, fully biomass‐based photothermal platform, which integrates abundant channel architectures, effective Th(IV) ion binding sites, and photothermal conversion ability, enabling synergistic achievement of selective thorium ion capture and efficient interfacial solar vapor generation. In scaled‐up outdoor experiments, after 9 h of solar illumination, a total freshwater yield of 13.7 L m −2 and Th(IV) adsorption capacity of 24.1 g m −2 are achieved by wood@PNs from thorium‐containing wastewater. Notably, ThO 2 with a purity of 99.2% and a cost‐effective price of USD 13.99 kg −1 could be produced from the recovery processes of desorption, concentration, and calcination. This work provides a novel biomass‐based solar‐driven purification platform, introducing a sustainable and economical strategy for nuclear resource recycling and clean water production.